This invention relates to high temperature transmission piping, and more particularly, to a rotary pipe coupling having apparatus for cooling the pressure seals.
In certain types of steam-driven electric generating systems, the steam pipelines must be shifted from one position to another. For example, a solar energy collection system which uses a fixed concentration mirror has a moving focal point wherein its location is dependent upon the relationship of the sun to the the mirror. To collect energy in such a system, the collection device must move through a wide range of positions during the day in order to maintain itself at the focal point of the solar radiation. If the energy is collected by means of converting water to steam, the piping must transport the steam at high temperature and pressure. Rotary couplings used in such a system must withstand both high temperature and pressure. Therefore, there is a need for a rotary joint that is mechanically reliable, has little gas or thermal leakage, and rotates with minimal friction.
High-temperature rotary joints and couplings are not new to the art, as shown by U.S. Pat. No. 3,057,646 to Brumagim which discloses a coupling that connects abutting steam pipes, and has a conduction path for carrying a fluid to cool the pressure seal. U.S. Pat. No. 2,127,073 to Topping illustrates an air-cooled steam pipe expansion joint in which the packing material is thermally isolated to some extent from the high-temperature gas. These devices, however, do not provide the pressure seal thermal isolation, design simplicity, and mechanical flexibility called for in current dynamic steam piping systems.